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### 11.13 Command Syntax and Function Syntax

Additionally to the function syntax described above (i.e., calling a function like `fun (arg1, arg2, …)`), a function can be called using command syntax (for example, calling a function like `fun arg1 arg2 …`). In that case, all arguments are passed to the function as strings. For example,

    my_command hello world

is equivalent to

    my_command ("hello", "world")

The general form of a command call is

    cmdname arg1 arg2 …

which translates directly to

    cmdname ("arg1", "arg2", …)

If an argument including spaces should be passed to a function in command syntax, (double-)quotes can be used. For example,

    my_command "first argument" "second argument"

is equivalent to

    my_command ("first argument", "second argument")

Any function can be used as a command if it accepts string input arguments. For example:

    toupper lower_case_arg
       ⇒ ans = LOWER_CASE_ARG

Since the arguments are passed as strings to the corresponding function, it is not possible to pass input arguments that are stored in variables. In that case, a command must be called using the function syntax. For example:

    strvar = "hello world";
    toupper strvar
       ⇒ ans = STRVAR
    toupper (strvar)
       ⇒ ans = HELLO WORLD

Additionally, the return values of functions cannot be assigned to variables using the command syntax. Only the first return argument is assigned to the built-in variable `ans`. If the output argument of a command should be assigned to a variable, or multiple output arguments of a function should be returned, the function syntax must be used.

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